Ibrutinib is a kinase inhibitor indicated for the treatment of mantle cell lymphoma, chronic lymphocytic leukaemia and waldenstrom's macroglobulinemia.
Ibrutinib is chemically is known as 1-[(3R)-3-[4-amino-3-(4-phenoxyphenyl)-1H-pyrazolo[3,4-d]pyrimidin-1-yl]-1-piperidinyl]-2-propen-1-one and structurally represented as below.

Ibrutinib is first disclosed in U.S. Pat. No. 7,514,444 and marketed as IMBRUVICA®. U.S. Pat. No. '444 is disclosed the Ibrutinib process, wherein 4-amino-3-(4-phenoxyphenyl)-1H-pyrazolo[3,4-d]pyrimidine is reacted with tert-Butyl 3-hydroxypiperidine-1-carboxylate and diisopropyl diazodicarboxylate to obtain intermediate under mitsunobu reaction conditions by converting the hydroxy moiety of the tert-Butyl 3-hydroxypiperidine-1-carboxylate to a better leaving group, thereby allowing a substitution reaction. Further it is converted to ibrutinib by deprotection of Boc and acylation with acryl chloride. The reaction steps as illustrated by the following scheme I:

U.S. Pat. No. 9,156,847 has disclosed another process for the preparation of ibrutinib intermediate, wherein the pyrazolo [3,4-D] pyridine-4-amine ring of ibrutinib is preared through cyclization with use of formamide acetate and the reaction steps are illustrated in the below scheme II:

According to this patent the process which is disclosed in U.S. Pat. No. 7,514,444 has a number of disadvantages, such as those associated with cost, efficiency and environmental disadvantages. For instance the Mitsunobu step may be wasteful, costly and cumbersome.
U.S. Pat. No. 9,296,753 has disclosed the crystalline forms A, B, C, D, E and F and their process for the preparation.
The present inventors of the present invention has developed an improved process for the preparation of Ibrutinib with high yield and high purity. The present process is cost effective and feasible in large scale production also. The present process avoids the mitsunobu reagent conditions also.